1. Field of the Invention
The present invention relates generally to the field of chainsaws.
More specifically, the present invention pertains to a novel device that measures a chainsaw chain cutting tooth for sharpening.
A chainsaw is a portable cutting tool generally powered by a two-stroke engine or electric motor that drives a chain linkage of cutting teeth and connecting members. Chainsaws are used for a variety of purposes, most importantly tree felling and limbing. They are used by consumers around the home for general maintenance, and in professional settings for a variety of tasks, including cutting firebreaks to slow a forest fire and for harvesting wood.
The major components in a chain saw are the engine, drive mechanism, guide bar, and cutting chain. The cutting chain is made of riveted sections of metal that include cutting teeth, which are sharpened blades that are specially shaped to cut through and remove material as it is fed around the guide bar. The teeth are generally made from chromium plate steel that have a sharp angular or curved corner with cutting edges along its upper and side plate. The teeth alternate on the left and right side of the chain around the perimeter of the guide bar, which operates to support the chain while in motion.
Chainsaw chains are categorized by their pitch and gauge. Pitch is defined as half the length of three consecutive rivets, while the gauge is the thickness of a drive link at a location wherein it fits into the guide bar. Each tooth includes a depth gauge or raker, which sits in front of the tooth and limits the depth of the cut with each pass of the blade. This prevents the chain from cutting too deep, which will slow the rate of cutting, and from cutting too high, which can make the saw difficult to control.
Over time and after use, the teeth on a chainsaw may become dull and uneven, eventually requiring sharpening. The sharpening operation must be completed on the top plate cutting edge of each individual tooth. Some individuals sharpen their own chain; however manufacturers recommend having a chain resharpened by an authorized technician or dealer. Proper equipment and skills is required to precisely file or otherwise sharpen a chain cutting tooth. While general filing tools are available at most hardware stores, they are not adapted to measuring the required angles and width for chainsaw chain teeth. The width of the top plate must generally be filed with a precision of ±0.001 inches, which is extremely difficult to accomplish with conventional tools. Further, the angle of the top plate must be within a given tolerance to provide a proper cutting engagement plane.
The present invention improves upon chainsaw measuring devices by allowing a consumer to accurately and quickly measure the necessary widths and angles required for sharpening a chainsaw chain cutting tooth. The device comprises a caliper tool capable of measuring the width of the top plate with a precision of at least ±0.001 inches, and includes a built in angular gauge for measuring the angle of the top plate cutting edge. This tool allows individuals to safely and quickly sharpen a chainsaw chain without the use of a professional sharpening service.
2. Description of the Prior Art
Several devices have been disclosed in the art that measure the angle of the top plate cutting edge and width of the top plate for proper chainsaw chain sharpening. Rein, U.S. Pat. No. 6,105,446 discloses a device for the measuring of saw blades that has a receptacle for the turnable bearing of a saw blade as well as a measuring spindle which, with respect to the saw blade, is held adjustable and is born swingably about an axis parallel to the saw blade axis. On the measuring spindle there are arranged two measuring edges which together enclose an angle and are placeable on the cutting surface and on the release surface of a tooth. The measuring spindle has a low inertia moment and a friction-free bearing. This arrangement of components permits a simple and dependable execution of the measurement, even by inexperienced personnel, and the measurements of saw blades with different tooth sizes or states of wearing-down. Devices such as these are large and costly, and are not intended for home use by an individual user, but instead are suited for a commercial setting.
Other designs disclose a device that sets and measures angles using calipers. Economaki, U.S. Pat. No. 6,766,583 discloses an angle gauge that, when used in conjunction with a caliper or other linear measuring device, improves both the precision and ease with which angles can be measured and set by allowing the user accurately to measure and set angles in fractions of degrees. Using the gauge, an angle formed by the gauge may be determined or set by reference to the linear distance measured by the caliper. These devices are adapted to measuring angles on large pieces of equipment, and are not designed for measuring the small angles required for a chainsaw chain.
Other designs disclose calipers that can measure to a precision of ±0.001 inches. Kim, U.S. Pat. No. 7,685,735 discloses an electronic caliper with an adjustable digital display. In an embodiment the caliper includes an elongated body and a display member that pivots or rotates relative to the elongated body. The display member may include a base member, which is coupled with the elongated body for translational movement along at least a portion of a length of the elongated body, and a display coupled with the base member for pivotal movement between a first orientation and a second orientation. While such devices are useful for measuring the width of the top plate to its required degree of precision, they are not adapted for setting the top plate angle.
The present invention utilizes a unique design that allows for measurement of the top plate width to a precision of at least ±0.001 inches, and properly sets the angle for the top plate cutting edge. This allows a consumer to safely and properly sharpen a dull chainsaw chain cutting tooth to the proper width and angle, thereby saving considerable time and effort with having the chain sharpened by a professional sharpening service. The present invention substantially diverges in design elements from the prior art and consequently it is clear that there is a need in the art for an improvement to existing chainsaw chain measuring tools. In this regard the instant invention substantially fulfills these needs.